(2) Gummy tumor of bone develops either under the periostum, in the substance of bone, or in the medullary canal. It is simply an intensification of the process found in the inflammatory form just described, the difference being that the cell hyperplasia is more abundant. Much of the new material collects in a circumscribed space, and being more rapidly formed and less capable of organization, it entails more profound lesions by its retrograde metamorphosis. Generally tumor of the bone is, therefore, a much more serious form of disease than osteo-periostitis. In the long bones the medullary canal is the usual seat of deposit. The bone becomes hypertrophied in a porous manner, the Haversian canals and canaliculi become enlarged and filled with a gummy material which resembles a solution of gum arabic. In the flat bones, especially the cranial bones, the cancellar tissue is attacked, and may cause a separation of the two tables, and often necrosis of one or the other plates results. If it happens to be the inner one which undergoes carious degeneration, brain symptoms will develop. (3) Dry Caries.—According to Virchow, dry caries is always due to syphilis. This affection is a miniature gummy ostitis. Around one of the vascular canals the gummy material is deposited, this gummy material being later absorbed, leaving a stellate induration. This goes on leaving a funnel-shaped depression, its point leading into the diploe, which may be plainly appreciated by palpation. The essential features of this caries is the fact that no sequestra are formed, no pus extruded, nor is the skin but rarely involved. The following is a case of syphilis in which osteo-periostitis developed: On January 22nd, 1909, R. B., age 35, white, a housewife, applied to the Medical Department of the University Hospital Dispensary for treatment, complaining of rheumatism in her back and a sore shin. The patient has been married 14 years and has had four children; the two eldest are the only ones now living. Three years ago she gave birth to a full-term child which only lived a few minutes after expulsion. One year later she gave birth to another child, which was not at full term, but about six months advanced. She says two days previous to this birth she fell down stairs and struck on her abdomen. When the child was born its thigh was fractured, and the physician who attended her said the fracture was caused by the fall.